Ideally, anyone who received a coronavirus booster vaccine with a BA.5 booster dose is half as likely to contract Sars-CoV-2 as people who only received unmodified vaccinations. Protection is better if more time passes between the last dose of the original vaccine and the BA.5 booster. This is how the current findings of the US Agency for Disease Control and Prevention (CDC) can be roughly summarized.
Vaccination breakthroughs after BA.5 boost up to 56 percent less often
Various boosters adapted to the Omicron variant of Corona have been available in the US since September. CDC experts have now evaluated the results of the national PCR testing system. About 360,000 results were examined Tests of adults who presented to one of the approximately 10,000 pharmacies with symptoms of Covid-19. The probability of this test being positive was then compared between those who had already received a BA.5 booster dose and those who had only received the unadapted vaccines.
Younger adults between the ages of 18 and 49 showed the best vaccination effect. Here, people vaccinated with a BA.5 booster became infected 30 percent less often if two to three months had passed between the modified booster dose and the last vaccination dose. If there were eight months between the two vaccinations, the chance of a vaccine breakthrough was 56 percent lower.
Unclear: Did the adaption of the vaccine help or was the vaccination up to date?
In older adults ages 50 to 64, the extra protection was 31 percent in the group where the interval between last vaccination and the BA.5 booster was two to three months and 48 percent when it was at least eight months. In the case of the elderly over 65 years of age, there was an additional protection of 28 and 43 percent, respectively.
However, these data should be interpreted with caution regarding the efficacy of dedicated reinforcers. Because the description does not say whether the adaptation of the vaccines has the decisive effect or the chronology of previous vaccinations. It is conceivable that the current fourth vaccination with an unadapted vaccine could have a similar effect.
Herd immunity is establishing itself: the waves of infections are decreasing for the time being
Also, it’s been a little over two and a half years since the booster vaccines were introduced Months past. This means that only a few statements can be made about the length of the protective effect observed. It is very likely that new infections will occur soon as a result of the new sub-variants of the virus. However, the picture in the United States is similar to that in Germany: the longer the virus spreads, the less new waves of infection spread. Herd immunity to SARS-CoV-2, long awaited at first, appears to be slowly establishing itself.